Limit wifi item edit content's max length to 500

Bug: 293199910
Test: manual - on "Add network"

(cherry picked from commit 855053ca4124f2d515b21c469096f8c18bd4829d)
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:092668676af741719d50ac0f121a8f8461aa21ad)
Merged-In: I303b8c6e0f3c3a1174a047ba98f302042e5db9ae
Change-Id: I303b8c6e0f3c3a1174a047ba98f302042e5db9ae
1 file changed